Photoelectron spectroscopy of the doubly-charged anions [MIVO(mnt)2]2- (M = Mo, W; mnt = S2C2(CN)2(2-): access to the ground and excited states of the [MVO(mnt)2]- anion.
Photoelectron spectroscopy of the doubly-charged anions [MIVO(mnt)2]2- (M = Mo, W; mnt = S2C2(CN)2(2-): access to the ground and excited states of the [MVO(mnt)2]- anion.
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双电荷阴离子 [MIVO(mnt)2]2- (M = Mo, W; mnt = S2C2(CN)2(2-) 的光电子能谱：接近 [MVO(mnt) 的基态和激发态
DOI：
10.1021/ja039652o
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发表时间：
2004
期刊：
影响因子：
--
通讯作者：
Wedd,AnthonyG
中科院分区：
文献类型：
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作者：
Waters,Tom;Wang,Xue-Bin;Yang,Xin;Zhang,Lianyi;O'Hair,RichardAJ;Wang,Lai-Sheng;Wedd,AnthonyG
用光剥离光电子能谱研究了双电荷配合物[MIVO（mnt）2]2-（M = Mo，W; mnt = 1，2-二氰基乙烯二硫醇根）的电子结构.这些二价阴离子在气相中是稳定的，并且是钼酶和相关钨酶的二甲基亚砜还原酶家族的活性位点的最小模型。测量了两种物质的绝热和垂直电子结合能，提供了有关母体二价阴离子的分子轨道能级以及产物阴离子[MVO（mnt）2]-的基态和激发态的详细信息。密度泛函理论计算被用来协助分配的分离功能。这些特征之间的能量差异提供了从S（π）和S（σ）分子轨道到产物[MVO（mnt）2]-的单占据金属基轨道的配体-金属电荷转移跃迁的能量。这些独特的数据MV物种在theC 2 v几何的父MIV dianions。然而，理论计算和可用的凝聚相数据表明，具有差异折叠的二硫杂环戊烯配体（Cspoint对称性）的几何形状的能量略低。配体折叠的驱动力是单占据的金属基分子轨道（a1 inC 2 v点对称性，最高占据分子轨道（HOMO））和最不稳定的硫基分子轨道（b1 inC 2 v点对称性，HOMO−1）之间的有利共价相互作用，这只有在还原到较低对称性时才可能。这种配体折叠诱导了Cs点对称下源自[MVO（mnt）2]-的HOMO−2的a' S（π）→ a' dx 2-y2电荷转移跃迁的预测强度的大幅增加。电子吸收光谱可用于相关物种[MoVO（bdt）2]-（bdt = 1，2-benzenedithiolato）和二甲基亚砜还原酶的氧化形式。在1.7eV处的强激发已被归属于S（σ）→ Mo跃迁，假定为C ~（2 v）几何构型。本文的工作表明，Cs几何的a' S（π）→ a' dx ~ 2-y ~ 2的可能性必须考虑.总的来说，这项研究证实，的M-二硫杂环戊烯单位的电子结构是非常敏感的二硫杂环戊烯配体折叠，加强建议，这些单位是可调的导管在酶系统中的电子转移。
Photodetachment photoelectron spectroscopy was used to investigate the electronic structure of the doubly charged complexes [MIVO(mnt)2]2-(M = Mo, W; mnt = 1,2-dicyanoethenedithiolato). These dianions are stable in the gas phase and are minimal models for the active sites of the dimethyl sulfoxide reductase family of molybdenum enzymes and of related tungsten enzymes. Adiabatic and vertical electron binding energies for both species were measured, providing detailed information about molecular orbital energy levels of the parent dianions as well as the ground and excited states of the product anions [MVO(mnt)2]-. Density functional theory calculations were used to assist assignment of the detachment features. Differences in energy between these features provided the energies of ligand-to-metal charge-transfer transitions from S(π) and S(σ) molecular orbitals to the singly occupied metal-based orbital of the products [MVO(mnt)2]-. These unique data for the MVspecies were obtained at theC2vgeometry of the parent MIVdianions. However, theoretical calculations and available condensed phase data suggested that a geometry featuring differentially folded dithiolene ligands (Cspoint symmetry) was slightly lower in energy. The driving force for ligand folding is a favorable covalent interaction between the singly occupied metal-based molecular orbital (a1inC2vpoint symmetry; highest occupied molecular orbital (HOMO)) and the least stable of the occupied sulfur-based molecular orbitals (b1inC2vpoint symmetry, HOMO−1) that is only possible upon reduction to the lower symmetry. This ligand folding induces a large increase in the intensity predicted for the a‘ S(π) → a‘ dx2-y2charge-transfer transition originating from the HOMO−2 of [MVO(mnt)2]-underCspoint symmetry. Electronic absorption spectra are available for the related species [MoVO(bdt)2]-(bdt = 1,2-benzenedithiolato) and for the oxidized form of dimethyl sulfoxide reductase. The intense absorptions at ∼1.7 eV have been assigned previously to S(σ) → Mo transitions, assumingC2vgeometry. The present work indicates that the alternative a‘ S(π) → a‘ dx2-y2ofCsgeometry must be considered. Overall, this study confirms that the electronic structure of the M-dithiolene units are exquisitely sensitive to dithiolene ligand folding, reinforcing the proposal that these units are tunable conduits for electron transfer in enzyme systems.